It is often required to carry pressurized fluid from or to an air conditioning or refrigeration system. For example, during initial charging or recharging of an air conditioning or refrigeration system refrigerant is added to the system. Typically, a refrigerant charging station is connected through a charging manifold to the air conditioning or refrigeration system. The manifold permits separate control of fluid flow from the charging station to a high pressure side port of the system and to a low pressure side port of the system.
The manifold typically also has a high side pressure gauge and a low side pressure gauge for providing pressure information to an operator. The manifold can be placed remote from the charging station and near to system for adjustment by the operator when in use. Continuing with the charging manifold example, the charging manifold is connected through hoses and fittings to the charging station and to the system. The fittings are generally connected to one another by threaded connections or quick disconnects. Other components can be utilized with the charging manifold. For example, an injector can be connected between the charging station and the system using additional fittings and hoses. Liquid dyes, lubricants, additives or other liquids can be injected into the air conditioning or refrigeration system using pressure from the charging station.
The various components that are directly or indirectly connected to the system make up an enclosed conduit for carrying fluids to the system. There are many other forms of such conduits. For example, manual injectors are in widespread use. These injectors are connected through hoses and fittings to the air conditioning or refrigeration system, and manual force is used to inject liquids from the injector into the system. Injection methods are described in many patents, see for example U.S. Pat. No. 6,263,778 entitled Precision Liquid Injection System issued Jun. 24, 2001 to Brass and Knecht describing a liquid injection device and co-pending International patent application number PCT/CA2004/00014 of Brass entitled Manual Liquid Metering Device and Cartridge filed 29 Jan. 2004.
Where a connection can be made between an injector and an air conditioning system with the injector and system in good alignment at the connection, and sufficient working space to operate the injector then, such a connection can be used. An example of a direct injection connection is described in U.S. Pat. No. 5,673,722 to Brass entitled Liquid Injection Device, System and Method issued 7 Oct. 1997.
The components in the conduit are typically made from metal, rubber or plastic sufficient to withstand pressures to be encountered in use. The materials must also be compatible with the fluids to be used.
Typically, there will be insufficient working space about the injector near the system to make a direct connection. Hoses are typically necessary to allow a remote fluid connection to be made to an air conditioning or refrigeration system, to allow access to a system in a confined location, or to allow an operator to work in a comfortable position.
Alignment of components in a conduit often requires bending and twisting of the conduit. It is usually the hoses that permit such twisting and bending. When using a charging manifold, the manifold may rotate and tilt on its support to permit some of the bending and twisting. In automotive applications, the manifold has a hanger and is typically hung from a rack at the charging station and, when required, hung from the underside of the hood of a car where the gauges can be viewed by an operator and the operator can actuate valves in the manifold to control the fluid flow between the charging station and the system. Rotation and tilting of the manifold can make it difficult for an operator to operate efficiently, as the operator may need to change positions in order to view the gauge, or reach out to tilt the gauge for proper viewing.
In some cases, a connection between fittings may have some play in order to provide some flexibility; however, the pressure in the conduit works against this, and stress on the fittings is undesirable. The pressure in the conduit can also work against twisting and bending of hoses in the conduit.
Considering again the need for conduits to carry pressurized fluids to and from air conditioning and refrigeration systems, such systems often leak. This leakage can reduce the efficiency of the system. A substantial loss of refrigerant and lubricant can also cause premature failure including compressor burnout. Also, refrigerants escaping into the environment are known to cause ozone depletion and, possibly, lead to global warming. Leak detection is generally performed by injecting a fluorescent dye into the air conditioning or refrigeration system.
Typically, injectors require a hose to convey the liquid from the injector reservoir or cartridge to the air conditioning or refrigeration system. For example, referring to FIGS. 1 to 4, a hose assembly for R134a systems has a 90 degree R134a female quick disconnect fitting 1 that is usually connected to a low side service port of the air conditioning system. These fittings 1 typically have an automatic shutoff when removed from the air conditioning system after the injection process is completed. Hose 2 is used to convey the liquid. Interface fitting 3 is used to connect the hose assembly to an injector reservoir or cartridge. Fitting 3 may be a screw on or quick disconnect type interface and may also include a check valve embodiment to prevent back pressure from the air conditioning system. The check valve will also prevent liquid from exiting the hose when removed from the injector.
Referring to FIG. 2, an R12/R22 embodiment similar to the hose assembly of FIG. 1 may be made by replacing fitting 1 with an R12/R22 fitting 4. It is to be recognized that fittings compatible with R12 and R22 refrigerant systems will also be compatible with many other types of refrigerant systems that use similar fittings. Hose assemblies for other types of systems that are not compatible with R134A or R12/R22 fittings can be easily made by replacing the fitting 1 or 4 with a compatible fitting.
Referring to FIG. 3, an adaptor fitting may be used to convert an R134a hose assembly as in FIG. 1 into an R12 or R22 hose assembly. In this embodiment a male quick disconnect 5 is fitted into fitting 1 of FIG. 1 in order to perform the conversion.
Referring to FIG. 4 there are many different injectors that can be combined with the type of hose described above. An example injector 11 has a spindle 6 which, when turned in a clockwise direction through injector body 7, pushes a piston in a cartridge 8 in a forward direction. Pushing the piston forward, forces the liquid in the cartridge 8 to open a check valve 9 further conveying the liquid through flexible hose 10 and further past R134a female fitting 12 into an air conditioning or refrigeration system. Total length 11 of an injection system can be up to 22 inches or more.
The inventors of the instant application have recognized these difficulties and that improvements to conduits for connection to an air conditioning or refrigeration system are desirable.